Hello. This is part 3 of our application and in that episode, we will integrate Recaptcha to a flask app on the backend. The frontend integration is done, but I will explain a bit also.

Frontend

On the front end, we just need to follow the steps from the google website. So what we can do is first import the script:

 <script src="https://www.google.com/recaptcha/api.js?onload=onloadCallback&render=explicit"
        async defer>
</script>

And the onloadCallback from the script we implement here :

var onloadCallback = function() {
    captha = grecaptcha.render('html_element', {
       'sitekey' : 'Website Key'
    });
};

html_element is the id of the Recaptcha element on the frontend like:

<div id="html_element"></div>

That element must be added to your form so it is submitted automatically with the content. And we can check if the Recaptcha is filled on the front by calling:

if( !grecaptcha.getResponse(captha) ){
    alert("Fill the recaptcha please !")
}

Backend

On the backend it is quick and simple:

We must just call the route https://www.google.com/recaptcha/api/siteverify

And we pass 2 parameters to the request:

{
  "secret" : "RECAPTCHA_SITE_SECRET",
  "response": request.form["g-recaptcha-response"] // from frontend
}

And as a complete code it gives:

response = requests.post("https://www.google.com/recaptcha/api/siteverify", data ={
        "secret" : os.environ.get("RECAPTCHA_SITE_SECRET"),
        "response": request.form["g-recaptcha-response"]
    })

    if(response.status_code == 200):
        data = response.json()
        if(data["success"]):
          pass // do something
    //do another thing is everthing is bad
          

The complete code can also be found here:

Thanks, and see you in the last part, where we will wrap the whole TTS app into a docker container and deploy it online.